On Fri 03-09-21 17:42:24, John Hubbard wrote:
> commit 6401c4eb57f9 ("mm: gup: fix potential pgmap refcnt leak in
> __gup_device_huge()") simplified the return paths, but didn't go quite
> far enough, as discussed in [1].
>
> Remove the "ret" variable entirely, because there is enough information
> already available to provide the return value.
>
> [1] https://lore.kernel.org/r/CAHk-=wgQTRX=5SkCmS+zfmpqubGHGJvXX_HgnPG8JSpHKHBMeg@xxxxxxxxxxxxxx
>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Cc: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Looks sane. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> mm/gup.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/mm/gup.c b/mm/gup.c
> index 9935a4480710..6e62f1518c1f 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -2241,7 +2241,6 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
> {
> int nr_start = *nr;
> struct dev_pagemap *pgmap = NULL;
> - int ret = 1;
>
> do {
> struct page *page = pfn_to_page(pfn);
> @@ -2249,14 +2248,12 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
> pgmap = get_dev_pagemap(pfn, pgmap);
> if (unlikely(!pgmap)) {
> undo_dev_pagemap(nr, nr_start, flags, pages);
> - ret = 0;
> break;
> }
> SetPageReferenced(page);
> pages[*nr] = page;
> if (unlikely(!try_grab_page(page, flags))) {
> undo_dev_pagemap(nr, nr_start, flags, pages);
> - ret = 0;
> break;
> }
> (*nr)++;
> @@ -2264,7 +2261,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
> } while (addr += PAGE_SIZE, addr != end);
>
> put_dev_pagemap(pgmap);
> - return ret;
> + return addr == end;
> }
>
> static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
> --
> 2.33.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
